The objective of this proposed research is to understand the subcellular mechanism of action of dihydroxyanthraquinone (DHAQ) on its anticancer activity. Simian virus 40 (SV40) will be used as an experimental tool to study the effect of DHAQ on chromosome structure and replication. The effect of DHAQ on SV40 chromosome structure will be analyzed based on the sensitivity of DHAQ-SV40 chromosome complex to the digestion of single-stranded specific and restriction nucleases. The effect of DHAQ on the modification (phosphorylation and acetylation) of histone (HI, H2a, H2b, H3, H4) and non-histone (viral capsid proteins, tumor antigen) proteins on viral chromosomes will be examined by polyacrylamide gel electrophoresis. Multiple forms of SV40 chromosomes found in cells after the exposure to DHAQ will be characterized as to their sedimentation values, protein/DNA rations, and nucleosome organization. The differential effect of DHAQ on DNA elongation and termination will be determined by the analysis of any accumulations of replicative DNA molecules in vivo and in vitro. Any effect of DHAQ on soluble factors required for DNA synthesis will be recognized by the complementation assays in vitro. The direct effect of DHAQ on the activity of partially purified DNA polymerases and DNA ligase will be studied first. To determine if the metabolities reveal the similar activity as does the parent compound, the 200S supernatant of cell lysate prepared from both infected and noninfected cells treated with DHAQ will be used to test for the inhibitory effect on SV40 DNA synthesis in vivo and in vitro. This research should provide insight information about the effect of anticancer drug on the structure of mammalian chromosome and chromosome duplication. The knowledege derived from this project will lead to the development of new and more effective anticancer compounds.